The present invention relates to a crash box for the bumper of a motor vehicle.
Nothing in the following discussion of the state of the art is to be construed as an admission of prior art.
Bumpers are typically arranged across the front and rear of a motor vehicle between the plastic shell of the vehicle body and the frame of the motor vehicle. To prevent damage to the vehicle structure in the event of a frontal crash or impact from the rear at low speeds, deformation elements are integrated which are also called crash boxes. Crash boxes are thin-walled elements, normally rectangular and made of steel, aluminum or plastic. They can be manufactured by joining compressed sheet metal shells or in single-piece construction, for example in the form of extruded aluminum section.
The crash boxes between the longitudinal member and the bumper cross member absorb kinetic energy generated in the event of an impact by converting the impact energy into deformation work. This prevents permanent damage to the longitudinal member when a critical stress level is exceeded.
German Offenlegungsschrift DE 100 14 469 A1 discloses a rectangular crash box composed of a top shell and a bottom shell. Embossments are formed in the crash boxes to realize a targeted deformation at a particular area. The crash box is supported on the end surface of the longitudinal member via a flanged plate. Screwed connections in the flanged plate connect the crash box to the longitudinal member. This requires in the area of the longitudinal member a suitably designed attachment zone, i.e. the presence of a respective flange.
German utility model DE 296 22 715 U1 discloses an impact absorber for a motor vehicle for engagement into the end of the bumper cross member. The impact absorber is hereby connected to the cross member by screws inserted transversely thereto.
Telescopic dampers which are pushed into the longitudinal member in the event of an impact are disclosed, for example, in International publication no. WO 99/15364 or U.S. Pat. No. 3,633,934. German Offenlegungsschrift DE 42 38 631 A1 discloses a shock absorbing structure for a bumper using an inner tube and an outer tube which are placed within one another, with the outer tube having a flange for support upon the longitudinal member. German utility model DE 298 08 143 U1 discloses a crash box which is secured to the longitudinal member by transverse bolts. As the crash box is attached on the side, the need for installation space is increased in a same way as the securement using flanges.
It would therefore be desirable and advantageous to provide an improved crash box which obviates prior art shortcomings and which is so constructed as to require little space so that available installation space can be utilized in an optimum way while having reduced weight and yet being reliable in the event of an impact operation.